Milling machine



Sept. 20, 1949.

5 Sheets-Sheet 1 Filed Dec. 2, 1943 IN V EN TOR.

a m am Q m.. w 7 2 Mm. w

Sept, 20, 1949. w, Dzus 2,482,729

MILLING MACHINE 5 Sheets-Sheet 2 Filed Dec. 2, 1943 -wwn Sept. 20, 1949. w. DZUS 2,482,729

MILLING MACHINE Filed Dec. 2, 1943 5 Shets-Sheet 3 W. DZUS 2,482,729

Sept. 20, 1949.

- MILLING MACHINE 5 Sheets-Sheet 4 Filed Dec. 2, 1943 t forneys I Sept. 20, 1949. w. DZUS'- 2,482,729

I MILLING MACHINE Filed Dec. 2, 1943 5 Sheets-Sheet 5 v IN V EN TOR. William 175745 Patentecl Sept. 20, 1949 UNITED STATES TENT OFFICE 4 Claims.

This invention relates to improvements in milling machines and more particularly to machines which may be used advantageously for producing slotted and grooved work, such for instance, as the slotting or grooving of fastener elements.

An object of the invention is the provision of an improvement in a machine of the indicated character, whereby to facilitate the insertion, removal, replacement and locking of the cutters whenever necessary or desired, and so that these operations, and others, may be readily carried out by women as well as men operators.

A further object is the provision of an improvement in a machine of the indicated character, whereby the cutter driving means is prevented from operating during removal and replacement of a cutter, as a safet precaution.

A further object is the provision of improvements in a machine of the indicated character, whereby to lubricate the cutters and work during the operation of the machine in such manner that the lubricant will be efiectually separated from the millings and chips, to the end that the lubricant will be constantly reused for facilitating the milling operation until .a change of lubricant is necessary, while the millings and chips are left readily accessible as scrap.

A further object is the provision of improvements in a machine of the indicated character which lend themselves to the efficient and expeditious operation of the machine; which enable adjustments and conversions for accommodating work of various sizes; and which conserve floor space and yet afiord places for finished and unfinished work, tools and other accessories.

With the foregoing, other objects of the invention will appear when the following specification is read in conjunction With the accompanying drawings, in which- Fig. 1 is a front view of a machine embodying the features of the invention, the machine being supported on any suitable structure at the desired elevation, it being shown on a stand, a portion of which is broken away;

Fig. 2 is a top plan view;

Fig. 3 is a side View with certain features shown in section;

Fig. 4 is an enlarged vertical sectional View of the work guide;

Fig. 5 is an enlarged vertical sectional view of the feed stock, portions thereof being broken away;

Fig. 6 is a fragmentary top plan and part sectional view of parts of the work guide, feed stock and opposed milling heads;

2 'Fig. '7 is a sectional view taken on the lin 'l-i of Fig. 4;

Fig. 8 is a vertical longitudinal sectional view of oneof the milling heads;

Fig. 9 is a sectional view taken on the line S9 of Fig. 8 and looking in the direction indicated by the arrows;

Fig. 10 is a face view of the actuator constituting a part of each milling head;

Fig. 11 is a sectional view taken on the line llii of Fig. 2 and showing the primary strainer tray in use in conjunction with the secondary lubricant separation means;

Fig. 12 is a top plan view of the chute for separating the lubricant and fine 'millings from the work and large chips;

Fig. 13 is an enlarged sectional View taken on the line l3-| 3 of Fig. 12;

Fig. 14 is a collective view of parts of the work guide and a rudimentary fastener in perspective;

Fig. 15 is a longitudinal sectional view of an unfinished or rudimentary fastener element;

Fig. '16 is a side view of the fastener element finished or slotted by the machine;

Fig. 17 is a sectional'top plan view of the feed stock, portions being broken away, and showing a Vernier to enable the adjustment of the screw driver at the desired angle and distance with respect to the work for an accurate setup in the operation of the machine;

Fig. 18 is a view of a longer fastener element and the screw-driver, said longer element requiring axial adjustment of the screw-driver;

Fig. 19 is an enlarged side view of the Vernier and parts with-which it cooperates;

Fig. 20 is a view to indicate what is meant by angular adjustment of the screw driver for changing relation of the kerf in the fastener element with'respect to the inner terminii of the slots; and

Figs. 21 and 22 are views of the main parts of the Vernier detached.

Referring now more particularly to Fig. 15, it will be apparent there is shown a rudimentary or unfinished piece of work in the form of a stud fastener element, consisting of a shank l0 having a head H on one end. The shank ID has a bore I2 therein extending longitudinally thereof, and said bore opens through the .end of the shank opposite that having the head H. The shank ID is therefore of tubular construction, The head II has a kerf l3 therein for the purpose of turning the fastener element. The finished piece of work or fastener element is shown in Fig. 16 The shank it of this prod-.-

uct has spiral slots l4 opposite each other. One wall of each slot is has a projection or hump l5. The slots M are designed and arranged to receive a cooperative spring fastener element. The projections i5 serve for the purpose of resisting retrograde rotation to prevent unintentional separation of the intereng-aged elements.

The machine of the present invention may be used for slotting the rudimentary fastener elements to produce the finished articles. It is to be understood the machine is not limited to the aforesaid use, but may be put to any and all other uses for which it is suited.

The machine includes a base or bed plate having an upstanding flange 2i all around its outer edge. Above the plate 28 are arranged a work guide 22, a feed stock 23, and a pair of opposed milling heads 24. In the present instance, these elements 22, 23 and 24 are all mounted on a hollow pedestal 25 which rests upon a resilient cushion 26 of cork or the like,

which cushion, in turn, rests upon an annular upstanding seat 21 disposed approximately centrally of the bed plate 26, as shown most clearly in Fig. 3. The pedestal 25 is secured to the seat 27 by bolts.

The work guide 22, which is shown most clearly in Fig. 4, includes a clamp bearing 29 rising from the pedestal 25 and integral therewith. A sleeve 30 is mounted in the bearing 29 in fixed position in a fore and aft direction. A slide 3| is arranged in the sleeve 30 for axial movement in opposite directions and is prevented from rotational movement by a key 32 engaged in a slot 33 and a groove or key-way 34 in the sleeve 39 and slide 3i, respectively. A block 35 is bolted to the bearing 29 and its upper end projects into the slot 33. The block 35 thus serves as a key to aid the bearing 29 in fixing the sleeve 36 in proper position. The key 32 and key-way 3-5 serve to limit the axial movement of the slide 3| in opposite directions in accordance with the required slots Hi. The slide 3! is reduced in diameter to provide a shoulder 35. A coil spring 31 is arranged within the sleeve 38 and surrounds the reduced portion of the slide 3i. Qne end of the spring 3'0 bears on the shoulder 36 and its opposite end bears on a tension adjusting nut 38 in threaded engagement with the sleeve 30. The spring 3? thus employed serves to cause the return or reverse movement of the slide 3!.

A work holder or chuck 39 is adapted for detachable articulation with the front end of the slide 3i so as to move axially therewith but prevented from turning with respect thereto. The chuck 38 consists of a body having a coaxial cavity 40 in its work-receiving end. Said end of the chuck has side openings or slots 4i arranged diametrically opposite each other and which communicate with said cavity 353. The other end of the chuck body is conical and loosely although snugly fits in a similarly shaped bore in the slide 3!. The chuck 39 has rearwardly opening notches 42 arranged diametrically opposite each other which receive lugs 43, respectively, on the front end of the slide 3| to prevent the chuck from turning with respect to the slide. The chuck is therefore detachable. The cavity 40 is so formed as to receive the shank of a rudimentary fastener element as shown in Figs. 14 and 15 with the head of the element projecting from the cavity, as indicated in Fig. 4. The fastener element or work piece is supported by the chuck to move axially therewith and to be turned with respect thereto. The openings or slots l 4 are positioned to receive rotary material-remov in cutters of the opposed heads 2d.

The feed stock 23 is for simultaneously moving the work axially in one direction and turning it in one direction, and then permitting the reverse movement of the work, as supported by the chuck es and guided by the slide 35. In other words, the machine tool 23 serves to feed or spirally drive the work to the cutters. The device 23 is best shown in Fig. 5 and includes a clamp bearing 44 integral with the pedestal A guide sleeve 45 is clamped by the bearing M in the required fixed position. A shaft All is supported by the sleeve 45 in axial alinement with the chuck it. The shaft 4? has axial and turning movement with respect to the sleeve 5. The inner end of the shaft il carries a screw driver #38. The said inner end of the shaft fil is split and formed to provide a collet 29. The inner end of the screw driver is bifurcated to provide a transverse slot 50. The shaft carries a transverse pin iii. The slotted end of the screw driver 38 is inserted into the collet 48 with the pin iii disposed in the slot 56. A tightening nut 52 constituting a part of the collet til, serves to secure the screw driver 48 to the shaft N. The pin 5i aids in preventing the screw driver 48 from turning with respect to the shaft 4?. Thus, the position of said edge is known and facilitates its engagement with the kerf IS in the Work piece. The sleeve 45 has an enlarged portion 53 on its outer end which has a slot 5 The slot 5 3 is spiral with respect to the axis of the shaft s'l. The portion $3 with its slot 5% constitutes a pattern cam to govern the movement of the shaft ll and the screw driver carried thereby. The shaft it! has an eniargement which moves in the sleeve portion 53 and said enlargement 55 carries a radial stud 56 on which is mounted a roller tl' disposed in the slot 5 and cooperating with the walls of the latter. The shaft s? has a handle 58 on its outer end for the purpose of pushing and turning the shaft subject to the action of the pattern cam. Thus, the screw driver it may be caused to move axially toward the chuck 39 and turn a predetermined distance, and also to move axially in the opposite direction and turn a predetermined distance as the shaft ti is turned one quarter of a revolution while moving axially.

The milling heads 21% are opposed to each other. Since these heads 2d are identical, a description of one will sufiice for both. Such head, shown most clearly in Figs. 8 and 9, includes a clamp bearing 88 rising integrally from the pedestal :25. A sleeve 64 is supported by the bearing for axial movement in opposite directions. The sleeve iii has a gear rack which meshes with a gear forming a part oi a holiow shaft 6i extending into a transverse bore (iii in the bearing 53. A bushing t9 tightly fitted to the wall of the bore 68 abuts a shoulder "iii of the shaft 6'1. A collar ii is keyed fast to the outer end of the shaft 67, as at it. The bearing 56 has a split i3 to provide a clamping portion which cooperates with the main portion of the bearing to set up the clamping action on the sleeve The collar "H bears on the portion M. The shaft 57 is prevented from moving axially by the bushing 59 and collar but permit it to be rotated. The collar 7! has external flats in which correspond to the internal flats it or" a separate actuator disk or the like l'l. This disk may be engaged with the collar 1 to cause the rotation of the shaft 67 when the sleeve fill is unclamped by the bearin I59. Upon rotation of the shaft 61, and through the intervention of the.

rack 65 and gear 96, the sleeve 64 may be caused to move axially between an advanced milling position and a retracted non-milling position. The sleeve 64 has a flange 1 8 which limits the movement thereof to the advanced position. In order to clamp the sleeve 54 in position there is provided a clamping bolt '59 which extends through the hollow shaft 87?. The threaded end 89 of the bolt is screwed into a nut 8i fixed to the bearing 68 in a recess therein. The bolt 19 has a head in the form of a nut 82, since said head has fiats 83. The head 82 also has a flange 84. The flats 83 correspond to the flats 18 of the disk TI so that the disk ll'inay be brought into engagement with the head 82 for the purpose of rotating the bolt 79. A washer 85 is interposed between the collar II and the head 82. Whenthe actuator disk ii is engaged with the head 82 it may be rotated to cause the axial movement of the bolt 79 in one direction to cause pressure to be exerted on clamping :portion M through the intervention of the parts 92, 85 and 'iI to clamp the sleeve 5 in fixed position to which it has been previously moved. By rotating the disk H in the opposite direction, the bolt I9 will be moved axially in a reverse direction, thereby releasing the pressure with the result that the sleeve 64 will be unclamped and free to be moved by means of the parts 77, H, 8?, 86 and t5.

The milling head also includes a hollow spindle 86 whose external diameter is smaller than the internal diameter of the sleeve 54. The spindle 86 extends coaxially of the sleeve 84 and is supported for rotation by roller bearings 8t, there being a pair of such bearings at each end of the sleeve 64, and said pairs are in spaced relation to provide a space 88 for lubricant. The spindle 86 is held against axial movement with respect to the sleeve 64 by the enlarged inner end 89 of the spindle which contacts one of said bearings 81, and a collar 99 fixed on the spindle 99 and in contact with another of the bearings 23?.

60, through a port 92 into the space 88 to lubricate the bearings 81. Ring packing or gaskets 93 seal the ends of the sleeve 54 around the'spindle to prevent leakage of the lubricant. An arbor 99 extends into the spindle 86 coaxially thereof. A conical collet 95 has a screw portion as in threaded engagement in a tapped socket in the inner end of the arbor 94. A lock pin 6i carried by the spindle 88 projects into a longitudinal groove in the collet 95 to prevent the latter from turning with relation to the spindle. The collet 95 cooperates with the conical end 59 of the spindle 86 in effecting the opening and closing of the collet. A head 9'! integral with the outer end of the arbor 94 bears on the outer end of the spindle 86 and also on a washer 98 which in turn bears on a lock nut 99 on the spindle. A second 1ock nut I99 on the spindle cooperates with the nut 99 to hold a lock washer I9! between them. The washer has a key engaged in a groove #32 in the spindle. A grooved pulley M3 is keyed fast to the spindle 88, as at I94. The nuts 99 and I00 cooperate with the collar 99 to aid in holding the pulley fixed to the spindle. The pulley I03 serves to transmit the power torque to the spindle 85 and the arbor 94 and its collet 95.

In order to hold the spindle from rotating so that the arbor 94 may be turned to open and close the collet 95 when the spindle is in the retracted position, there is provided means as Lubri cant flows from a cup 9| carried by the bearings foll c'ii'ivri upstanding bracket or rigid support I05 is fixed to a lateral arm 62 integral with the pedestal 25 by securing elements I09.

that purpose. end thereof secured to the bracket by screws I99 and the upper end of the spring I88 bears on the head end of the pin I81. The pulley I93'has a- 1. plurality of holes H9 therein, each opening:

through the outer side face thereof. The holes H8 are so positioned that the pin I81 may be entered into any one of the holes when the: spindle assembly is in the retracted position, as: indicated in dotted lines in Fig. '8. This wil1'pre-' vent turning of the spindle 86, although the arbor may be turned relatively to spindle. The head 91 has radial holes I I I to receive a handle bar for the purpose of turning the arbor. By turning the arbor'94 counter-clockwise, the collet will be moved axially out of the engagement with the conical end 89, due to the screw 95, thereby opening the collet and releasing a milling cutter II2. A clockwise turning of the arbor will close the collet 95 to grip the cutter II2 as will be understood. By engaging the actuator disk Ill with the collar II, the spindle assemblymay be moved axially in the manner set forth hereinabove, to either the advanced position in which the cutter may perform its material removing operation, or be moved to the retracted position for the insertion and replacement of the cutter.

The provision of the means to prevent rotation of the spindle while inserting and replacing a cutter also serves as a safety precaution.

The cutters II2 of the opposed heads 24 are in axial alinement with respect to each other and lie in the plane of the axes of the chuck 39 and the screw driver 48, and at a right angle with respect thereto. The cutters H2 are received in the slots M, respectively, of the chuck 39 when the spindle assemblies of the heads 24 are in the advanced position.

The pulley I03 of each head 24 is driven by means of any electric motor H3 through the intervention of a grooved pulley I I on the motor shaft and a belt H5 which encircles the pulleys I93 and 4. Separate motors are provided since it is preferred to use identical cutters. Obviously, the cutters I I2 are rotated in opposite directions. Each motor is supported on a bracket I IE5 integral with the bed plate 29. By adjusting the position of each motor, the belt may be tightened or loosened for proper operation.

A system is provided whereby the cutters and the work are lubricated, and whereby the work is separated from the lubricant and the lubricant is strained to free or separate the same from the millings and chips, during the operation of the machine. In accordance therewith, the chuck 39 has a longitudinal pa'ssageI29 therein which communicates with the slots or side openings 4| and a passage I2I extending through the slide 3I. A conduit I22 is connected with the outer end of the slide 3| by suitable fittings and said conduit includes a flexible section I215 which compensates for the axial movement of the slide 3I. The conduit I22 leads to a suitable pump which draws the lubricant or oil from a sump, said pump and the sump being omitted from the drawings. The oil is fed through the conduit I22, slide 3| and chuck 39 to bathe the cutters H2 and the work piece. The oil passes out of the openings 4| and, together with millings and small chips, fall through a chute I24 which has slots or other A headed.

stop pin I01 extends loosely through the'bracket,.- the latter having a transverse hole thereinfor' A leaf spring I88 has the lower" aesaraa openin s I525 for that pu pose... The chute. is; of ng lar f rmation and has depending flange. I26. with notches. I21. Screws. its are received; in the notches. I2 r snectivebr. and secure he chute to the block 35 so that the chute isv dis-. posed directly beneath. the chuck 39-. as shown in. Fig. 4. The finished piece of work is dropped into the chute I24. Which delivers it to a. suitable receptacle I29, indicated in dot-andflaizih lines. in 2. The large chips, if any, also are, delivered by the chute into.v the. receptacle. 121 A. similar receptacle or. tray I29, indicatedv in dots and-dash lines in Fig. 2, holds the new worls. These receptacles are at the front of the machine.

As stated, the oil and millings. pass through the. openings I25 in the chute... An inclined. trough. I38 formed in the pedestal; 25 catches the oil and millings and conveys the same, to, a receptacleor tray having a strainer bottom. tray is. indicated in dotted lines in Fig. 2 and also. appears; in full lines in Fig. 11 and is designated I3}, The receptacle rests on ribs I32 on the uhper surface. ofthe bed plate 20. The ribs; I 32 serve as spacing means to hold the receptacle elevated so. that. the oil may flow through the bottom while millings.

are retained in the receptacle. The oil leaving the receptacle I3I passes into a separation res ceptacle subdivided into two compartments I33.

and I34, respectively, by an overflow partition I35. A strainer I36 is seated on the plate 28' at the top of the compartments. The oil leaving the tray I3I flows into the compartment I33.

Any fine particles still remaining in, this oil drop.

to the bottom of the compartment I33. The clear oil flows over the top of the partition I35- into the. compartment I34 from which it flows through a return conduit I31 to the sump. The oil is thoroughly strained and is constantly reuseable until a change is necessary.

The machine is used as follows. A rudimentary fastener element is placed in the chuck 3.9.: by inserting its shank It in the cavity 40. This is done while the cutters H2 are in operation and the chuck is in its normal position. A pushing force is then applied to the handle 58' which compels the simultaneous axial and turning move, ment of the screw driver 48. The axial movement toward the work piece occurs somewhat before the turning movement, according to the pattern of the cam 53, in order to provide leeway. The screw driver is engaged with the work piece caus ing it to move axially a'predetennined distance supported by the chuck and guided by the slide 35 and simultaneousl therewith, the work piece is turned relatively to the chuck one fourth .Of a revolution with the result spiral slots I4 are cut into the work piece. The spring 3'! isv compressed. By pulling on the handle 58, the screw driver 48 is retracted and at the same time the spring 3'3 reacts to return the slide 3I and chuck .39 to the normal position, enabling the removal of the finished fastener element from the chuck, said element being dropped to the chute {2.4 which delivers it to the receptacle I23. These operations are repeated for quantity production, The oil is. constantly circulated during the operation of the machine in the manner and for the stated pure poses.

In Figs. 17, 19, 21 and 22 are shown a Vernier or gage for making and indicating adjustments of the screw driver .48 at the desired angle and dis: tance with respect to the work piece II) for an ac.- curate setup in the operation of machine. This is desired in order to obtain a definite relation the inner termini of the slots 14 with respect l to the. kerrand; the depth or the slots with respect. to, the. head II, or in other words, the axial. travel of the work piece Ill with respect to the cutters H2;

The Vernier 01F gage I46 consists ofa. collar k4}. nut I42 and indicator I43. The collar I.4I has a nipple. I44 which has a male thread to receive. the nut. I42 which is tapped correspondingly. The. collar carries a. thumb screw M5 The circular face of the collar has a scale I46 graduated. from zero. to 360 degrees. The circular face of the nut. has a scale I4 graduated from zero to 5.0. The nut M2 is knurled to facilitate the turningof the nut. on the nipple I44. The collar [AI is arranged on the sleeve 45 which has. a longitu-. dinal groove I48 therein. The collar I4I together with the nut I42 carried by the former may be slid back and forth on the sleeve 45. The screw I45. is receivable. in the groove. I48. and when tightenedsecures the collar to the sleeve. 45. The indicator I43 is secured in fixed position on the clamp bearing 44 by screws I49.

When after an approximate setting of the screw driver 48. it is desired to accurately adjust the angular position of the screw driver on the axis provided by the shaft 41, the parts MI and I42 are slid on the sleeve 45 to a position in which the nut I42 abuts the bearing 44. The screw N15 is then tightened to lock the collar on the sleeve 45. A reading is then taken as indicated on the scale I45 by the indicator I43. The bolts of the clamp bearing 44 are loosened after which the sleeve 45 and parts carried thereby are turned in the proper direction, thereby changing the angular position of the screw driver ili to the desired position as indicated by the Vernier. The bolts of the bearing 44 are tightened to hold the sleeve 45 and associated parts in the position. Thus it is possible to obtain a definite relation of the inner terminii of the slots I54 respect to the kerf I3 when the slots are out. 7'

With the parts MI and I42 locked on the sleeve 45 with the nut I42 abutting the bearing 44, the Screw driver 4 may b set t the p o er dis tance h r rd to e ork pie e onsideri its length and the depth of skits l4 desired with p c t e head I l.- A read n is th n. ta en as indicated the s a :41 b th mean i s he s e ve 4 is unclaimed as a rsse d- The t I 2 is then t r ed d y easo sl s e d en a ement with the n le M4 at? contact with the bearing 44 the sleeve .45 and parts carried thereby, includin the screw driver .3. may be moved axially to the desired eds rately adjusted position indicated on the Vernier scale I41 by the indicator I43. The sleeve is t e lamped by ti h i the bo ts of he bearing 44.

In 17 are shown dotted lines a, b, c; and a, The line it indicates the center of t hecutters l I2 The distance between the lines a and b indicates the degree of axial movement of the screw driver 48. The line 0 indicates the starting position oi the edge of the screw driver. The distance be: tween lines o and d indicates the amount of axial adjustment of the screw driver required to. .oper: ate properly on t e lon er astener e eme t shown in Fig. 1.8, and which adjustment the l d a cu e ettin is ac m ishe y th use of the Vernier forthepurposes stated.

The ma ne may he s t o supported in any u able manner at the desired elevation. In the present instance, the machine is set on a stand B8 which has various compartments and places for finished and unfinished work, tools and other accessories.

It is to be understood the invention is not restricted to the illustrated embodiment thereof, but that changes may be resorted to and details of construction may be modified and rearranged in accordance with the appended claims.

I claim:

1. In a machine tool, a stationary support, an axially movable spindle assembly mounted in said support, a rotary hollow shaft extending in a transverse bore in said support, said assembly having a gear rack, a gear on said shaft meshing with said rack, a clamping bolt extending through said shaft, a nut fixed to said support in threaded engagement with the inner end of said bolt, said support embodying a clamping portion, means on the shaft operable to rotate said shaft to move the spindle between an advanced position and a retracted position through the intervention of said rack and gear, and means on said bolt operable to turn said bolt to exert pressure on said clamping portion to clamp the spindle in position.

2. In a machine tool as set forth in claim 1, and a separate actuator which may be optionally used With said means on the shaft to rotate the shaft, or used With said means on the bolt to turn the bolt.

3. In a machine tool, a spindle, means mounting the spindle for axial movement between an advanced active position and a retracted inactive position enabling the insertion and removal of a tool, means for driving the spindle, and means adapted to cooperate With a part of the driving means when the spindle is in its retracted position to prevent the rotation of the spindle, said part having holes therein, and said last means consisting of a fixed support, a stop pin slidable in said support and receivable in any one of said holes, and a spring in set relation to said pin to yieldingly bear on one end of said pin to hold it in the selected hole.

4. In a machine tool, a spindle, means mounting the spindle for axial movement between an advanced active position and a retracted inactive position enabling the insertion and removal of a tool, a pulley fast on said spindle for driving it, said pulley having a circular series of spaced holes therein, a fixed support, a stop pin movable back and forth in said support, said pin being receivable in any one of said holes when the spindle is in its retracted position to prevent the rotation of the spindle, and a spring on said support which yieldingiy bears on one end of said pin to hold it in the selected hole.

' WILLIAM DZUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,616,151 Thacher Feb. 1, 1927 1,630,328 Brumbach May 31, 1927 1,697,698 Sundstrand Jan. 1, 1929 1,991,500 Eklind Feb. 19, 1935 2,016,365 Dumser et al. Oct. 8, 1935 2,026,448 Turrettini Dec. 31, 1935 2,038,235 Phillips Apr. 21, 1936 2,109,969 Dzus Mar. 1, 1938 2,153,424 MacRae Apr. 4, 1939 2,178,130 Zwick Oct. 31, 1939 2,227,620 Armitage et al. Jan. 7, 1941 2,290,061 Matia July 14, 1942 2,366,247 Fauser Jan. 2, 1945 

